Ann: Gold Extraction Results from Ema and Tres Estados, page-213

The few hundred dollars referred to conventional petrographic examination under reflected or transmitted light. This is called optical mineralogy

( https://en.wikipedia.org/wiki/Optical_mineralogy )

and there are many professionals in the this field that can be turned to assist in the identification of minerals .

As I said in a previous post

https://hotcopper.com.au/threads/an...605856/page-184?post_id=26728212#.WZ-nQme6ztQ

should optical mineralogy fail to identify the species of sulphide/compound then you can progress to microscopes that examine, image and analyse the elemental make up of a compound using a beam of accelerated electrons, an electron microscope.

https://en.wikipedia.org/wiki/Electron_microscope

There are also microscopes that can resolve things to small atomic scales

https://en.wikipedia.org/wiki/Scanning_tunneling_microscope

https://en.wikipedia.org/wiki/Atomic_force_microscopy

The article that you have referenced in your post relates to a completely different field of science called X-ray crystallography (or crystallography).

https://en.wikipedia.org/wiki/X-ray_crystallography

https://en.wikipedia.org/wiki/Crystallography

that uses very high energy electromagnetic radiation, X-Rays, to determine the atomic and molecular structure of crystals.

An unusual gold-silver sulphide like uytenbogaardtite can be completely visible and identifiable with the naked eye or under an optical microscope (in the case that the sulphide crystals are small and disseminated in the rock), but its full crystalline structure (like all minerals) can only be determined properly using high energy radiation like X-Rays. The pattern of transmitted X-Rays is computed back to reconstruct the arrangements (and symmetry groups) of the atoms in the crystal lattice which will help explain certain physical properties of the crystal (mineral) like the various shapes/forms it has in nature etc.

Below is an image of uytenbogaardtite plainly visible in reflected light at what seems like a low magnification. Below that is another image of the same sulphide clearly visible with the naked eye (1mm scale crystals). No need for any fancy microscopes with that sample. Probably also no need for any fancy assays either.

It's OK if you want to remain Comfortably Numb, some of us prefer solid explanations of things.

Eshmun

Uytenbogaardtite New Bullfrog Mine, Nye County, Nevada, reflected light low magnification (you can see it!!!!!) Colour (Grey-white)

http://www.webmineral.com/specimens/picshow.php?id=3051&target=Uytenbogaardtite#.WZ-1PWe6ztQ